This site is like a library, use search box in the widget to get ebook that you want. Greens function solution equation gfse for 2d laser heating problem involves a twodimensional integration formula. Therefore, laser materials processing has been usually associated to high heating and cooling rates. Femtosecond laserinduced periodic surface structures on. The surface structures generated in the air environment at normal.
In dielectrics, we find qualitative differences in the. Prokhorov general physics institute, ras, moscow, russia abstract nanosecond laser heating of liquid metal film al, thickness 430 nm, initial number of particles 5. C, a continuous wave co2 laser was used as the radiation source. Two mechanisms have been previously proposed for the reduction in surface roughness, namely. Laser beam interaction with materials for microscale applications. Confidence can be established via a fundamental understanding of the physics of the process. Heating up metal takes time, therefore, slow marking speeds should be used. Save up to 80% by choosing the etextbook option for isbn. Part 2 basic regimes of the heating of metal targets by laser irradiation. Understanding and predicting relationships between laser welding process parameters, such as laser speed and welding power, and meltpool characteristics have been the subjects of many studies in literature because. Mihailescu, laser heating of metals adam hilgeriop publishing, bristol, 1990. Basic regimes of the heating of metal targets by laser irradiation 3.
The present paper part 1 and the following paper part ii will focus on theoretical and experimental studies, respectively. Laser heating and resistance heating are two heating methods that are commonly used in heat assisted microforming processes. One advantage of this algorithm is that the method can be efficiently used to obtain results of any desired accuracy. Ceg is about 2 ps or smaller if lattice heating is taken into account. The beadonplate welding experiments were performed using a 3 kw nd. Critical parameters for the considered al model are tc 7600 k, pc 1400 bar. Interband electronic excitationassisted atomicscale. Optical and thermal properties of metals, ceramics, and cvd diamond films upon hightemperature laser heating. Laser heating of metals download ebook pdf, epub, tuebl. The role of airflow in enhancing laser interactions with metals has been studied for some time. Characteristics of radiation absorption in metallic particles. In order to ensure efficient use of lasers, and for any largescale implementation, a thorough knowledge of the fundamental laws governing the interaction of radiation with matter. Maiman at hughes research laboratories, based on theoretical work by charles hard townes and arthur. It is shown that copper singlecrystal surfaces can be patterned by laser light.
The purpose of this work is to investigate energy transfer in multilayer metals during shortpulse laser heating. The absorptivity on a smooth processing front is homogeneously governed by the angledependent operating range of the corresponding fresnelcurve. The word laser started as an acronym for light amplification by stimulated emission of radiation. Simultaneous target heating, plasma spectral emission, and time. Recent developments of optical devices make it possible to obtain almost any arbitrary pulse shapes. Laser powder bed fusion additive manufacturing of metals. A greens function model for the analysis of laser heating of. Laser heating of metals a m prokhorov bok 9780750300407. Saturable absorption during highintensity laser heating of. High power density, such as laser beam, has been increasingly utilized in industrial manufacturing. The present paper part 1 and the following paper part ii will focus. Laser evaporation of htsc films is used widely in the fabrication of structurally perfect epitaxial films. Surface overmelt during laser polishing of indirectsls.
Interaction of highpower laser light with materials often causes irreversible damage of the nearsurface region. Annealing possibilities using the conventional method of annealing, the laser is used out of focus to get a large laser spot for heating the material and the marking speed is set very low becauseheating takes some time. The interaction of highintensity, shortpulse laser radiation with liquids is fundamental to many contemporary technologies. Laser devices for heat treatment of metal materials co 2 laser uses a mixture of co 2, n 2 and he gasses, ensures a reliable operation, stable output and a high quality of the laser beam profile. Scaling laws for melting and resolidification in direct. Femtosecond fiber laser welding of dissimilar metals. Particularly, special attention has been paid to the femtosecond laser heating of thin. Laserinduced damage threshold measurements were performed on homogeneous and multilayer dielectrics and goldcoated optics at 1053 and 526 nm for pulse durations. Derrien, remi torres, thierry sarnet, marc sentis, and tatiana e. Laser radiation provides the most suitable choice for the purpose of heating the material during microforming process as it offers several advantages in comparison to other methods, including 35.
Investigation on hot cracking during laser welding by means. Using a double temperature model with nonlocal heat flow and a laser pulse length of 1 ps, the calculated surface temperatures of the electron and phonon subsystems are presented for cu, nb, and pb. Analysis article pdf available in international journal of heat and mass transfer 3717. However, little experimental demonstration besides some theoretical works 12, has been published for fs laser welding of dissimilar metals. As laser heating softens the material, the airflowinduced pressure difference between front and rear faces causes the metal to bulge into the beam. The maximum of the current pulse is delayed relative to the laser pulse, its duration exceeds. A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation.
This is compared with the results of a local heat flow approach and with the conventional theory as well. Heating a metal target subjected to pulsed laser radiation. As laser heating softens the material, the airflowinduced pressure difference. Laser welding was carried out at increasing distances parallel to the free edge. However, estimations of some important thermal and optical properties in the existing twotemperature. During ultrashort laser pulse interaction with metals, the heat transfer. The term laser originated as an acronym for light amplification by stimulated emission of radiation. The process of laser beam in solid material offers a great potential for the new product design, for example, welding, cutting of metals, drilling of holes, laser shock hardening and laser glazing. Nonequilibrium laser heating of multilayer metals, however, has not been studied. However, the transition of this technology from production of prototypes to production of critical parts is hindered by a lack of confidence in the quality of the part. Improved twotemperature model and its application in.
These integrals are performed using rombergs integration algorithm. Laboratoire hubert curien, umr cnrs 5516, 42 000 stetienne, france. Pdf femtosecond laser heating of multilayer metalsi. A highspeed video camera was used to monitor the plume and keyhole behaviour. Yag laser with a power of 1100 w and welding speed of 10 mm s. Laser pulse heating of surfaces and thermal stress analysis materials forming, machining and tribology 9783319000855. Irradiation with green light produced adatoms and vacancies, which selforganized into nanoscale pyramids. Heating and melting model induced by laser beam in. Laser processing of metals is based on the flow of heat that is generated by the. Gold coatings were found, both experimentally and theoretically, to be limited to 0. Aspects of heat flow in laser processing of metals diva portal. Reflectivity as a function of wavelength for different metals han, 2005. Formation mechanisms of femtosecond laserinduced periodic surface structures on silicon thibault j.
Work has also been done on laser zone melting of htsc compounds, but we shall not deal with the methods. In the literary material that has been surveyed and presented i found the book laser. Phase transformations during laser processing of aerospace. Canadian journal of physics canadian science publishing. In order to make sure environment friendly use of lasers, and for any largescale implementation, a radical information of the basic legal guidelines. Experiments with a highpower laser beam directed onto thin aluminum sheets, with a large spot size, demonstrate that airflow produces a strong enhancement of the interaction. A l mikhailichenko, g n mikhailova, a m prokhorov, a s seferov, a v troitskii, a o mednikov institute of general physics. Pdf interaction of a highpower laser beam with metal sheets. The absorptivity of a laser beam interacting at grazing incidence with the processing front during laser welding, cutting, or drilling depends on the metal to be processed and on the laser wavelength. At low laser intensities, the classical model of absorption and heating applies, which assumes a constant absorption coefficient and no dependence on intensity. Pdf on dec 6, 2016, marco minissale and others published laser remote heating in vacuum environment to study temperature dependence of optical properties for bulk materials. Pdf on dec 6, 2016, marco minissale and others published laser remote heating in vacuum environment to study temperature dependence of optical properties for bulk materials find, read and cite. Prokhorov laser heating of metals world of digitals.
Laser welding of metals involves with formation of a meltpool and subsequent rapid solidification, resulting in alteration of properties and the microstructure of the welded metal. Optical and thermal properties of metals, ceramics, and cvd. Phase transformations in laser processed metallic materials usually occur under very high temperature gradients and during a short time. Improved twotemperature model and its application in ultrashort laser heating of metal films the twotemperature model has been widely used to predict the electron and phonon temperature distributions in ultrashort laser processing of metals. Pdf laser remote heating in vacuum environment to study. In the present study, attenuation of the laser beam because of the induced plume during beadonplate welding of an austenitic stainless steel plate with a 15 kw fibre laser beam, was investigated to better understand laser welding phenomena. Slm makes it possible to create fully functional parts directly from metals without using any intermediate binders or any additional processing steps after the laser melting operation 3. Reviews of topical problems related content nonlinear. Modeling of ultrashort laser pulsetrain processing of metal.
Estimation of the absorptivity of a constructive material at. Laser heating of metals provides a systematic and comprehensive presentation of the fundamental principles underlying the physical and chemical mechanisms governing the interaction of laser radiation with solid targets, and in particular metals in gaseous environments, for a. Click download or read online button to get laser heating of metals book now. The enhancement is explained in terms of aerodynamic effects. Laser heating of metals provides a systematic and comprehensive presentation of the fundamental principles underlying the physical and chemical mechanisms governing the interaction of laser radiation with solid targets, and in particular metals in gaseous environments, for a wide range of beam parameters. Various different critical parameter values for al and other metals are given in ref. Interaction of a highpower laser beam with metal sheets. Melting and resolidification processes in direct sls can have significant effect on the temperature distribution, residual stress, and the final microstructure quality of the parts. Formation mechanisms of femtosecond laserinduced periodic.
Direct selective laser sintering sls of metals is a process in which a highenergy laser beam directly consolidates a metal powder or powder mixture to full density. Traditionally, heat treatment of metals involved heating in an oven, flame, by induction, or electric arc above a critical temperature to achieve a crystal phase. So the most suitable laser type for heat treatment is a continuous co 2 laser. Thermal radiation absorption in metallic particles is an important phenomenon in many contemporary laser processing techniques, including laser cladding of coating materials and laser cleaning of particulate contaminations. In this usage, the term light includes electromagnetic radiation of any frequency, not only visible light, hence the terms infrared laser, ultraviolet laser, xray laser and gammaray laser. Laboratoire lasers, plasmas et procedes photoniques lp3. Dec 29, 2015 the production of metal parts via laser powder bed fusion additive manufacturing is growing exponentially. Tsarkova, optical and thermal properties of metals, ceramics, and cvd diamond films at high temperature laser heating, in proceeding of the prokhorov general physics institute, vol.